Development of light-sensitive silver halide emulsions



United States Pate Ofliee. Passed 23 11 1123 silver halide layers by means of the usual developers. 3,523,796 Consequently these compounds can be considered as de- DEVELOPMENT OF LIGHT-SENSITIVE velopment accelerators Jozef g i f f fi ?f gg g g js Sels, Itis also known, however, that a noticeable increase 1n tich, and Robrecht Julius Thiers, Brasschaat, Belgium, 5 sensltlvliy only obtained Wm} these compounds when assiguors to Gevaert-Agfa N.V., Mortsel, Belgium, a developmg in rather slow workmg developers of the fine company of Belgium grain developer type used in the development of con- No Drawing. Filed Aug. 9, 1967, Ser. No. 659,334 tinuous tone images. In fast acting p-N-methyl-ammophe- Claims priority, application Great Britain, Aug. 30, 1966, nol hydroquinone or l-phenyl-3-pyrazolidinone hydro- 2/ quinone developers, their development accelerating ac- Gosc 5/30 tion manifests itself only by a very moderate increase of 9666 4 Claims the speed of the developed photographic material.

- e It is further known that these compounds when used in silver halide emulsion layers of the more sensitive type ABSTRACT OF THE DISCLOSURE impair the keeping qualities of these layers, particularly Photographic light-Sensitive Silver halide materials at high temperatures and elevated degrees of relative comprising a Polymeric Compound containing humidity, since they induce a substantial increase of fog. alkylene-amino groups in base of Sail form linked It also has been observed that the incorporation of these through hydroXy-shhstituied oxyalkyieile groups are compounds into the photographic material in order to Sefibed- The Polymeric Compounds in the Silver halide prepare more sensitive silver halide emulsion layers immaterials increase the developability and sensitivity of pairs th image t f th develo ed ilve thereby the photographic emulsion. forming brown and reddish brown images.

It has been found now that polymeric compounds containing N-alkyl-alkylene-amino groups in base or salt This invention relates to a Process for Producing a form linked through hydroxy-substituted oxyalkylene P aphic silver image by de e opment of exposed groups and such polymeric compounds wherein the hylight-sensitive silver halide in the presence of compounds drogen atoms of the said hydroxy groups are partly or influenc ng the Sensito e ric Characteristics Q a g wholly substituted, are very suitable for substantially insensitive silver halide emulsion by an increase of the creasing the developability and also the sensitivity of Speed and/01 the g The Present nt on a photographic silver halide emulsion layers on develop- Telaies to Said Compounds used in Said P their ment in slow as well as in fast acting developers, and preparation and t0 photographic materials and ppractically do not impair the keeping qualities of the said ing baths containing said compounds. layers.

It is known that the general Sensitivity of P phic Polymers, which have proved to be very suitable in emulsions, which can already be sensitized optimally that respect, contain structural units which are reprethroughout the Whole range of the spectrum y means of sented by the following structural Formulae A and B: the so-called chemical sensitizers, such as sulphur sensitizers, can be increased if amines or some polyamines H I such as diethylenetriamine, triethylene-tetramine, are N-Alk1-O-CH2-CH-Alkz-CHOH2- added to these photographic emulsions (British specifica- L 6 6 L tion 734,474 filed Nov. 6, 1953, by Kodak). Such substances, however, cause an increase of the free silver ion A L 0R1 OR: B OR: OR: -|u

concentration of the emulsion and greatly diminish its wherein:

stablllty' R represents a C -C alkyl group including a substituted It 1s also known that an increase of sensitivity can be C1435 alkyl group, e'g methyl ethyl, propyl, isopropyl obtained by incorporating mto the photograph1c material or z hydroxyethyl or an aralkyl group 60g benzyl polyethylene glycols alkylepe oxide polymers obtallled each of Alk and Alk represents an alkylene group conby polymerising alkylene oxide in the presence of hexrtol taming from 2 to 10 carbon atoms, including Such ring dehydration products, aliphatic alcohols, aliphatic group Substituted by 6% a hydroxyl group and/Or acids, amines, amides, and phenols (British specifications such group the carboll chain of which is interrupted by Nos. 548,019, filed Mar. 19, 1941, by Kodak; 600,058, hetero atoms, fig oxygen, Sulphur, phosphorus or a filed Jan. 10, 1946, by Du Pont de Nemours; 592,676, b t d h 1k b H ted filed Apr. 20, 1945, by Du Pont de Nemours; 748,745, f 'i igg fif atom as an a y and 748,750, both filed June 28, 1954, by Kodak). n is apositiveinteger of atleast 3 and It is further known that these polyglycols and alkylene R1 represents a hydrogen atom, an alkyl group including oxide polymers should possess a molecular Weight of at Sub ted 1k 1 m an th la n cu least 400. In order to obtain a noticeable effect, it is in a S1 u a y g e y y 1 n e gr practice necessary to use compounds having a molecular aO-Rz, C-N-R2 or -SO2R2 weight of 1500 to 2000 and more. N H

Contrary to the other known methods for increasing the sensitivity of silver halide emulsions such as those in wherein R represents an alkyl group, a monovalent unwhich the chemical sensitizers increase the inherent sensaturated aliphatic group such as an alkenyl group, an sitivity and those in which the cyanine dyes increase the aryl group or a heterocyclic group including said spectral absorption, it appears that the final sensitivity groups in substituted form. of the silver halide emulsion layers in which these com- 7 The compounds according to the invention can be prepounds are incorporated is higher since these compounds pared by reaction of a monoalkyl-hydroxyalkylene-amine exert a favourable influence on the development of these and/ or di(hydroxyalkylene)-amine with a bis-epoxide.

The polyaddition is carried out in such a way that the polyaddition products either in the form of the base or in the salt form are soluble in water.

If the reaction between the secondary amine alkanol and the bis-epoxide is too exothermic, care must be taken that the reaction mixture is cooled in order to prevent the formation of gummy products. The optimum reaction temperature is adapted to each polyaddition and usually varies between 50 and 180 C.

When very reactive starting compounds are used, it is sometimes advantageous to mix the reaction products with water at the stage at which the required degree of polyaddition is attained, so that any further addition, which would lead to the formation of water-insoluble products, is prevented. Normally, polymers containing both types of structural units A and B are formed but depending on 1 mole of a secondary amine alkanol is preheated at a temperature comprised between and 130 C. (see Table l), and subsequently 1 mole of a bis-epoxide is added thereto portion-wise whilst stirring. The addition of the bis-epoxide is regulated so that no gummy products are formed; if necessary the mixture is cooled during the addition. After the addition of the bis-epoxide, the reaction mixture is allowed to react further (see Table 1) in order to obtain products with a higher molecular weight. Care should be taken, however, that the reaction is stopped when formation of water-insoluble gummy products begins. With very reactive starting products it is sometimes necessary to add water to the reaction mixture after the addition of the bis-epoxide to avoid gum formation.

In Table 1 hereinafter a survey of suitable starting products and reaction conditions is given.

TABLE 1 Used epoxide 6 HN-(CHZCH2OH)2 the reactivity of the respective hydroxyl and secondary amino groups one of both units will dominate in the structure of the polymer.

In general, the starting products are made to react in an equimolar ratio, though an excess of one of them is not harmful in most cases, except in a polyaddition reaction between very reactive compounds, in which an excess of bis-epoxide should be avoided always in order to prevent the formation of polyaddition products, which either in the form of a base or a salt are insoluble in water. Bisepoxides suitable for use are, e.g., 1,2:5,6-diepoxy-hexane, bis(2,3-ep0xypropyl)ether, 1,2 bis(2,3 epoxypropoxy)- ethane, 1,3-bis(2,3-epoxypropoxy)-propane, 1,4-bis(2,3- epoxypropoxy) butane, 1,3 bis(2,3 epoxypropoxy)-2- propanol, 1,3-bis(2,3-epoxypropoxy)-butane, 2,3:2,3-diepoxy-N-alkyl-dipropylamine, 5,6-epoxy-hexane carboxylic acid-2,3-epoxypropyl ester, bis(2,3-epoxypropyl)-sulphone.

Tri-epoxides such as tri(2,3-epoxypropoxy)-phosphate and 2,4,6-tri(2,3-epoxypropoxy)-s-triazine can also be used.

Particularly suitable secondary amine alkanols are N- alkyl-ethanolamines such as methyl-, ethyl-, propyl-, isopropyl-, and butyl-ethanolamines, N-alkyl-propanolamines, e.g., N-methylisopropanolamine, N-a-methylbenzylethanolamine, etc.

As an illustration of the preparation of said polyaddition products a general procedure of preparation is given hereinafter.

Reaction temp Reaction time Remarks Water-soluble viscous mass.

Viscous mass, soluble in Idem.

Water-soluble viscous mass.

Idem.

3 h Idem.

In the preparation of condensation products according to the present invention wherein the hydrogen atoms of the free hydroxyl groups are partly or wholly substituted reagents of the type of those reacting with an active hydrogen atom are used, e.g., an acid chloride or acid anhydride such as acetic anhydride, succinic anhydride, or maleic anhydride, a sulfonyl chloride, an isocyanate or an unsaturated alkylating compound, e.g., a vinyl compound such as acrylonitrile and methacrylonitrile. The reaction product of the hydroxyl-containing polymer with maleic anhydride is preferably allowed to react with a bisulphite thus forming a bisulphite addition product. The bisulphite used is preferably an alkali metal bisulphite. The bisulphite addition compounds applied in the present invention are very less fog-producing and are therefore preferred for being incorporated into the light-sensitive material. The preparations of the compounds 7 to 12 are given to illustrate these reactions.

COMPOUND 7 To a solution of 24.6 g. (0.1 mole) of compound 5 in 200 cos. of dioxan, a solution of 19.6 g. (0.2 mole) of maleic anhydride in cos. of dioxan is dropwise added at reflux temperature in /2 hr. An oily precipitate is formed and refluxing is continued for 4 hrs. whilst stirring. The dioxan is then decanted from the viscous oil, which is extracted several times with warm dioxan and thoroughly kneaded with ether. The residue is dried at 60 C. The product obtained is fatty and water solu' ble. Yield: 39.5 g.

COMPOUND 8 To a solution of 13.7 g. (0.05 mole) of compound 3 in 100 ccs. of dioxan, a solution of 9.8 g. (0.1 mole) of maleic anhydride in 50 ccs. of dioxan is dropwise added at reflux temperature in min. An oily precipitate is obtained and refluxing is continued for 4 hours whilst stirring. The dioxan is then decanted from the viscous oil, which is extracted several times with warm dioxan and thoroughly kneaded with ether. The residue is dried at 60 C. The product obtained is fatty and water-soluble. Yield: 23.5 g.

COMPOUND 9 To a solution of 13.85 g. (0.05 mole) of compound 4 in 100 ccs. of dioxan, a solution of 9.8 g. (0.1 mole) of maleic anhydride in 50 cos. of dioxan is dropwise added at reflux temperature in 15 min. An oily precipitate is obtained and refluxing is continued for 3 hours whilst stirring. The dioxan is then decanted from the viscous oil, which is extracted several times with warm dioxan and thoroughly kneaded with ether. The residue is dried at 60 C. The product obtained is fatty and soluble in dilute sodium hydroxide solution. Yield: g.

COMPOUND 10 To a solution of 20 g. (0.2 mole) succinic anhydride in 150 ccs. of tetrahydrothiophene-l,l-dioxide, a solution of 27.7 g. (0.1 mole) of compound 4 in 100 ccs. of tetrahydrothiophene-l,l-dioxide is dropwise added at 100 C. in 30 min. Heating is continued for 3 hrs. whilst stirring. The solution is then poured into a mixture of ether and aceton (1000 ccs./ 300 ccs.) and a viscous oil is obtained which thereafter is still three times kneaded with the same mixture. The residue is dried in a drying oven at 60 C. The product obtained is a water-soluble resin. Yield: 47 g.

COMPOUND 11 To a suspension of 23.6 g. (0.05 mole) of compound 9 in 200 cos. of water, 10.4 g. (0.1 mole) of sodium bisulfite in 100 ccs. of water are dropwise added at room temperature. The mixture is then refluxed for 5 hrs. whereby a solution is obtained. The solution is filtered otf, evaporated and dried in the drying oven at 70 C. The product obtained is a water-soluble resin. Yield: 33.5 g.

COMPOUND 12 To a solution of 11 g. (0.025 mole) of compound 7 in 100 ccs. of water, 5.2 g. (0.05 mole) of sodium bisulfite in 50 ccs. of water are dropwise added at room temperature. The mixture is refluxed for 5 hrs. and the solution is filtered, evaporated and dried at 70 C. The product obtained is a Water-soluble resin. Yield: 14.5 g.

The development accelerators used according to the present invention can be added as a base or in the salt form to the coating composition of a silver halide emulsion and/or incorporated into a water-permeable layer, which applied under or on top of the emulsion layer for-ms a water-permeable system with the silver halide emulsion layer and thus can come into effective contact with the silver halide.

The development accelerators can be incorporated into the coated emulsion layer either by treating the emulsion layer with an aqueous solution of these development accelerators or by coating this layer with a water-permeable layer containing the development accelerators, or also by bringing the development accelerators from a Waterpermeable layer lying under the emulsion layer and comprising said development accelerators, by diffusion into effective contact with the silver halide.

The water-soluble development accelerators can be added to the light-sensitive silver halide emulsion during different preparation steps of the light-sensitive material:

for instance they can be incorporated therein as a separate addition either mixed with one or more ingredients, which are used in the preparation of the silver halide grains during the physical or chemical ripening process, or another moment preceding the application of the emulsion.

The development accelerators are preferably added to the silver halide emulsion composition after the chemical ripening process and just before coating the emulsion.

The development accelerators are preferably added in dissolved form in water or in an aqueous mixture of water and water-miscible organic solvents that do not impair the photographic properties of the light-sensitive silver halide emulsion. When the polyaddition products are not sufliciently soluble in water in their base form, they are converted into their salt form by neutralization, e.g., with an acid such as sulphuric acid, hydrochloric acid, p-toluenesulphonic acid, or acetic acid.

The optimum amount of development accelerator added to the silver halide emulsion depends on the very compound, on the nature of the colloid binding agent for the silver halide grains, and on the amount and the kind of the silver halide in the emulsion. In general, however, the development accelerators are added to the lightsensitive material in amounts ranging from mg. to 10 g. per mole of silver halide. In the developing bath they are normally used in amounts ranging from 0.1 g. to 10 g. per liter. If necessary, these compounds can also be added in amounts exceeding these limits.

The step of increasing the sensitivity according to the present invention can be combined with a method known as chemical sensitisation, in which together with the above-mentioned development accelerators usual amounts of chemical sensitisers are added to the silver halide emulsion, e.g., sulphur-containing compounds such as allyl isothiocyanate, allylthiourea or sodium thiosulphate, reducing compounds such as the tin compounds described in our Belgian patent specifications 493,464, filed J an. 24, 1950, and 568,687, filed June 18, 1958, both by Gevaert Photo-Producten N.V., the iminoaminomethane sulphinic acid compounds described in the British patent specification 789,823, filed Apr. 29, 1955, by Gevaert Photo-Producten N.V., or noble metal compounds such as gold, platinum, palladium, iridium, ruthenium, and rhodium compounds. As a matter of fact, the sensitising action of the development accelerators used in the present invention comes in additiorr to the sensitising action of the sensitising compounds originally present in gelatin.

The development accelerators applied in the present invention can also be used in combination with stabilisers and fog-inhibiting compounds for the silver halide emulsion, for instance with mercury compounds or organic sulphur-containing compounds that form an insoluble silver salt with silver ions, preferably heterocyclic nitrogen-containing thioxo compounds such as benzothiazolin- Z-thione and l-phenyl-tetrazolin-S-thione, the compounds described in our Belgian patent specifications 571,916 and 571,917, both filed Oct. 10, 1958, by Gevaert Photo- Producten N.V., and compounds of the oxytriazolopyrimidine type, e.g., 5-methyl-7-hydroxy-s-triazolo[1,5-a] pyrimidine. The combination with sensitising and stabilising cadmium salts in the light-sensitive material as well as in the developing bath can also be applied.

Other compounds, which sensitise the photo-graphic emulsion by development acceleration, such as organic onium compounds and polyonium compounds, preferably of the ammonium or sulphonium type, e.g., quaternary tetra-alkylammonium salts, alkylpyridinium salts, bisalkylene-pyridinium salts, alkylquinolinine salts and trialkyl-sulphonium salts can be used together with the development-accelerators according to the invention in the developing solution as well as in the light-sensitive material. Other ingredients, such as colour couplers, developing substances, hardening agents, and wetting agents, can also be added to the emulsion in the ordinary way.

The development of low-sensitive as well as of highsensitive, of fine-grain as Well as of coarse-grain silver halide emulsions is accelerated by the action of the abovementioned development accelerators. These products can be applied for accelerating the development of X-ray emulsions as well as of the most difierent spectrally or nonspectrally sensitised emulsions. They can be incorporated into the photographic emulsion either with or without optical sensitisers and can be used for increasing the sensitivity of negative emulsions as well as of positive emulsions.

The following examples illustrate the invention.

EXAMPLE 1 A washed negative gelatin silver bromo-iodide emul sion (average grain size of the silver halide. 0.8 the silver halide of which consists of 94.5 mole percent of silver bromide and 5.5 mole percent of silver iodide, is ripened at 45 C. The emulsion ready for coating contains per kg. 50 g. of silver halide, 75 g. of gelatin, 30 mg. of optical sensitiser according to the following structural formula:

50 mg. of S-methyl-7-hydroxy-s-triazolo[l,5-a]pyrimidine as a stabiliser, and 500 mg. of saponine as a wetting agent.

This emulsion is divided into several aliquot portions and to the separate portions is added one of the development accelerators according to the present invention. The emulsion portions are separately applied to a cellulose triacetate support and dried.

The test strips obtained are then exposed in the same conditions through a grey wedge and developed for 7 minutes at 20 C. in a fine-grain developer of the following composition:

Water800 ccs. Monomethyl-p-aminophenol sulphate2 g. Hydroquinone-5 g.

Anhydrous sodium sulphite100 g. Boraxg.

Boric acid5 g.

Potassium bromide-0.5 g.

Water to1000 ccs.

The speed is given in exposure values which have to be compared with the exposure value of an emulsion to which no sensitiser was added. A decrease of the exposure value by means a doubling of the speed.

Amount of compound per Sensitometric results Number of the kg. of emuladded compound sion (g.) Fog Gamma Speed EXAMPLE 2 Example 1 was repeated but the emulsions contained the development accelerators listed in the following table.

Before development the emulsion strips were conditioned for 36 hr. at 57 C. in an atmosphere of 34 percent relative humidity.

8 EXAMPLE 3 The sensitometric results are listed in the table hereinafter.

Amount of compound added added per kg.

Sensitometric results Added compound emulsion Fog Gamma Spec d EXAMPLE 4 An emulsion as described in Example 1 is used, except that the test strips after having been exposed, are developed for 8 min. at 20 C. in a developer having the following composition:

N-methyl-p-aminophenol sulphate-4.5 g. Sodium sulphite, anhydrous-100 g. Boric acid-2.2 g.

Sodium chloride-45 g.

Water to1000 ccs.

The sensitometric results are listed in the table hereinafter.

Amount of compound added Sensitometrie results added per kg. Added compound emulsion Fog Gamma Speed 0. O7 0. 52 186 300mg 0.09 0.50 162 300 mg 0. 10 0. 56 175 300 mg". 0.11 0.67 152 300mg. 0.10 0.52 178 300 mg 0.10 0. 52 168 1g- 0.13 0.62 163 EXAMPLE 5 An emulsion as described in Example 1 is used, except that the test strips after having been exposed, are developed for 8 min. at 20 C. in a developer having the following composition:

Water (52 C.)-750 ccs. N-methyl-p-aminophenol sulphate-2 g. Sodium sulphite, anhydrousl00 g. Hydroquinone-S g.

Borax, granular2 g.

Water to-1000 ccs.

The sensitometric results are listed in the table hereinafter.

Amount of compound added Sensltometrle results Amount of added per kg. COIIfiDOUFd pelr Scnsitometric results Added compound emulsion Fog Gamma Speed 'g. o emu Added compound sion (mg) Fog Gamma Speed 0.10 0.48 187 Polyethylene glymg 0. 28 0. 58 0. 08 0. 52 124 col with average Polyethylene glycol 100 0. 50 0. 53 11-; molecular weight with average mo- 6, 000 lecular weight 6,000. 300 mg Completely logged 9 10 EXAMPLE 6 R represents a hydrogen atom, an alkyl group, a sub- A washed negative coarse-grained gelatin silver bromosmutfid alkyl group or a iodide emulsion, in which the silver halide consists of F 2 r 1 a r up 98.2 mole percent of silver bromide and 1.8 mole percent 0 0 H of silver iodide, is ripened at 42 C. After addition of 5 630 mg. per mole silver halide of 5-methyl-7-hydroxys-triazolo[1,5-a] pyrimidine as a stabiliser and other uswherein R represents an alkyl group, a monovalent unsaturated aliphatic group or a heterocyclic group including said groups in substitution form, and

ual ingredients, the emulsion is coated on a support nisapositive integer of at1east3 p 2. Process for developing photographic materials con- Othef samples are Prepared by add11 1g separately to taining light-sensitive silver halide according to claim 1,

determined amounts of the same emulsion before coatwherein R1 represents a ing, the hereafter indicated amounts of developing ac- COOH celerator. They are then processed in the same manner as Sample 1.

After d yi and gp samples a developed 15 group or its bisulphite addition product. f 4 In a Solutlon havlng the followmg cOIHPOSI' 3. A photographic light-sensitive material comprising tron: a silver halide and a polymeric compoundcontaining the Water 800 ccs. following structural units or these umts in salt form:

Monomethyl-p-aminophenol sulfate-4 g. l 'I Sodium sulfite (anhydrous)65 g. l O C 2 I 2 H C Hydroquinone-IO g. 0R1 0R1 n Potassium bromide5 g.

Water to 1000 Cos each of Alk and Alk represent an alkylene group containing from 2 to 10 carbon atoms wherein said chain may contain elements such as oxygen, sulphur, phos- Amount Meow Sensitomemc results phorus, and nitrogen directly linked to two carbon po d pe atoms of said alkylene chain,

Added compound emulswn Gamma speed R represents an alkyl group of 1 to 5 carbon atoms, a

gg g2 substituted alkyl group, or an aralkyl group, 1 66 R represents a hydrogen atom, an alkyl group, a substituted alkyl group or a What we claim is: -R?,%, IT-Rz or --SO2R2 1. Process for developing photographic materials con- 40 o 0 H taining light-sensitive silver halide which comprises the wherein R re resents an all: 1 rou a monovalent step of developing said materials m the presence of a 2 p y g p unsaturated aliphatic group or a heterocyclic group inpolymeric compound, containing the following structura cluding said groups in substituted form, and umts these umts 111 Salt form: n is a positive integer of at least 3.

4. A photographic light-sensitive silver halide material l 1 according to claim 3 containing said polymeric com- I 0 1 0 J pound m an amount ranging from 100 mg. to 10 g. per

mole of silver halide.

L 0131 OR: OR: OR: |n wherein: References Cited each of Alk and Alkg represent an alkylene group con- UNITED STATES PATENTS taining from 2 to 10 carbon atoms wherein said chain may contain elements such as oxygen, sulphur, phos- 3,245,793 4/1966 Smlth 96*35 phorus, and nitrogen directly linked to two carbon atoms of Said alkylene chain, NORMAN G. TORCHIN, Prunary Examiner R represents an alkyl group of 1 to 5 carbon atoms, a E. C. KIMLIN, Assistant Examiner substituted alkyl group, or an aralkyl group, 

